GPUImageMovieWriter: Added `cancelRecording` method (almost the same as `finishRecording`).
GPUImageMovieWriter: Added method to finish writing with completion block. It uses new iOS 6 API of AVAssetWriter while preserving backward compatibility.
GPUImageVideoCamera: Prevent creation of another capture device when changing movie writer.
Merge branch 'feature/writer-finish-cancel' into develop
Disabled assertion. It seems to work.
Changes to fix incorrect release of filter's target.
Merge branch 'master' of git://github.com/BradLarson/GPUImage
Merge branch 'master' of git://github.com/BradLarson/GPUImage
Add `finishRecording` method with completion block (with backward compatibility)

iOS 6 SDK and higher: If writer responds to async method, call it, otherwise call synchronous method and completion handler.
iOS 5 SDK and lower: Call only synchronous method and completion handler. The rest should not be even compiled.
Fix case of nil completion handler, `AVAssetWriter` does not accept it.
Improved `finishRecording`
Fix 2 warnings
Fixing FBO size when it should return zero-sized value.
Fixing crash if effect's target was nil.
last updates to examples and merge resolving
Merge pull request #826 from sromanuk/master

Issue when effect has no targets
Merge pull request #823 from iMartinKiss/pullrequest/finishRecording-iOS6

Add `finishRecording` method with completion block
Added a motion blur filter.
Incorporated Jacob Gundersen's fixes to the Voronoi filter, fixed the naming of it across the framework.
Added a zoom blur.